"Execute against Japan": The U.S. Decision to Conduct Unrestricted Submarine Warfare

Introduction

1 At 1752 Eastern Standard Time on Sunday, December 7, 1941, about four and a half hours after the initial chaos unleashed by the Japanese attack on Pearl Harbor, the U.S. Navy’s Chief of Naval Operations released a simple but dramatic message: EXECUTE AGAINST JAPAN UNRESTRICTED AIR AND SUBMARINE WARFARE.1 It was 0652 on Monday, December 8, in Manila. It was 1222 on December 7 in Pearl Harbor.2 With the orders to conduct unrestricted warfare, all Japanese shipping, from fishing trawlers to freighters to tankers, became valid targets. Because civilian crews manned most of these ships, unrestricted warfare meant that these civilian sailors would be treated like combatants, not innocent noncombatants whose lives were to be spared at all costs. Unrestricted warfare not only directly targeted civilians at sea, it also indirectly targeted millions of civilians in Japan, who suffered starvation and privation. The later U.S. strategic bombing campaign, which would kill numerous Japanese noncombatants, came toward the end of hostilities. The unrestricted war against all maritime shipping, however, started at the very beginning of the war and did not end until Japan’s surrender. Thus, well before the United States accepted civilian casualties as collateral damage in the strategic bombing campaigns, U.S. unrestricted warfare struck at Japanese civilians both at sea and on shore. The decision to conduct unrestricted warfare was a major and dramatic change to the American attitude toward freedom of the seas. From its inception , the United States had strongly stood out for the right of commerce to sail the world’s oceans at all times without the threat of attack. Admittedly, Introduction 2 Introduction the American view toward freedom of the seas evolved from 1776 through 1941, but the United States remained a consistent advocate and protector of noncombatant merchant ships and sailors. The strength of this conviction was demonstrated in 1917, when President Woodrow Wilson placed German unrestricted submarine warfare at the center of the U.S. decision to enter the First World War. Two decades later, President Franklin D. Roosevelt echoed Wilson’s views as he assailed German unrestricted submarine warfare as one of the greatest threats to American freedom and security, as well as a crime against humanity. Unrestricted submarine warfare was specifically and unambiguously illegal . The United States was a signatory to both Article 22 of the London Naval Treaty and the London Submarine Protocol of 1936. The two documents, which were identical, stated that submarines were required to remove a merchant ship’s crew to a place of safety before that ship could be sunk. A place of safety, furthermore, was not considered to be a lifeboat on the open sea. It did not matter if the merchant ship belonged to a belligerent nation or a neutral nation. It did not matter if a merchant ship was arguably in the service of a belligerent nation’s war machine. Regardless of origin or ownership, merchant ships could not be attacked without warning. As war became inevitable, however, unrestricted warfare became a far more attractive option to U.S. naval strategists. Well before Pearl Harbor, with no documented approval from the civilian chain of command, the senior naval leadership of the United States decided to commence unrestricted warfare almost immediately upon the inevitable outbreak of hostilities. Although future writers attempted to portray the orders to conduct unrestricted warfare as a spur-of-the-moment decision made in the wake of the Pearl Harbor attack, the orders were really the result of a year of debate and consideration by the U.S. naval leadership. By abruptly ordering unrestricted warfare in December 1941, the United States effectively turned away from the notion of Wilsonian freedom of the seas and the noncombatant nature of merchant ship sailors. The decision was such a significant about-face that diplomatic historian Samuel Flagg Bemis wrote: “Thus did the United States forswear and throw overboard its ancient birthright, the Freedom of the Seas, for which it went to war with Germany in 1917 and collected adjudicated indemnities, after the victory, for torts against its own citizens by illegal German submarine warfare, 1914–1918.”3 Another Introduction 3 historian, Janet M. Manson, asserted even more dramatically: “no other foreign policy reversal in U.S. history quite matches in magnitude [this] decision .”4 Had unrestricted submarine warfare not been clearly essential to the U.S. victory over Japan, it might well have become...